Telephone system.



PATENTED AUG. 14, 1906.

H. G. WEBSTER. TELEPHONE SYSTEM.

APPLIOATION FILED Imc. 15, 1902.

mimi/aww iran estaras T OFFICE.

ILLINOIS, ASSlGNOh TO KELLOGG COMPANY, Ol? CHICAGO, MLINOIS, A

vetements SYSTEM.

Specification of Letters Patent.

Patented Aug. 1&1., 1906.

' Application led December l5. 1902: Serial No. 165,235-

To' all whom itmfiy concern,.-

Beit known that I, HARRY G. WEBSTER, a citizen of the United States, residing at Ohi-v cago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone Systems, of which the following is a specification.

My invention relates to telephone systems, and more particularly to the type in'which a common battery or batteries'are provided at the central office to furnish the substations with currentfor transmission pur oses and for the operation ofthe various relays associated with the lines.

My invention has for its objects to provide a system which is extremely simple and in whichthe various operations of connecting subscribers 'for conversational purposes may be carried out in a rapid and efficient manner.

' The iigure is a diagram of two subscribers stations and the central-office apparatus associated therewith.

L and L2 indicate subscribers lines extending in two limbs 2 and 3 from their respective substations to the central oflice. At the substations-fof example, at the station A, located upon tht line L-the apparatus includes an Ordinar,T bell 4 and a condenser 5', connected between the line conductors, and a transmitter 6 and a receiver 7, connected in a bridge of the line which is normally open at the switch-hook 8. This arrangement is intended' merely to typify any usual or desired common-battery subscribers outfit.

At the central o'Hice the sleeve-conductor. 3 includes the Iwindingof the line-relay R and is thence connected by a common lead 9 with the live pole of a battery B. The said relay controls a local circuit of the line-signal S through its normally open contacts, Iwhich are joined by conductor 10 with the normal contact of grounded springl 11 of the line-cut-of relay R2. The tip-conductor 2 of the line is normally grounded by means of a branch 12, extending to a normal contact of the grounded spring 11. This conductor also includes anon-inductive resistance 13 ofpreferably about two hundred ohms and is thence connected by conductor 14 with the tip-contacts of th spring-jacks of the line of which there is an answering-jack J, together with any suitable number of multiple jacks, such 1 as J2 and J3. The sleeves of these jacks are connected by conductor 15 with the sleeveline L2 is similar to the line L, but is connect ed at the central oflce with the same battery by means of a second common branch 9 and is The ca bells at these stations are legged to ground from the different line conductors.

The opcrators outfit includes 'a cord-circuit, consisting of a plug VP and a calling-plug P2, the tip-contact of the plug P being connected by the tip-strand t, the condenser c, and the sleeve-strands2 \.itli the sleeve-contact of the'plug P2, while the sleeve-contact of plug P is likewise joined by the sleevestrand s, the condenser c2, and the tip-conductor t2 with the tip-contact of the plug P2. Asupervisory signal S2 is connected between the tip-strand t and the live pole of the battery 'B by means of conductor 18, which includes thc normal contacts of a supervisory relay 1', which is in turn connected between the sleeve-strand s and the same pole ot' the battery. A supervisory signal S3, associated with. the other plug of the cord-circuit, is similarly connected with the tip-strand t* by means of conductor 19 and likewise includes the normal contact of the supervisory relay r2, which is connected between the sleeve-strands2 and the live pole of the battery. Retardation-coils 20 and 21 are connected across the answering and calling ends, respectively, of the cord-circuit and are preferably about three thousand ohms resistance. The operators receiver 22, the secondary of her induction-coil 23, and the condenser c3 are bridged-across the calling end of the cord? vcircuit by means ofthe springs 24 of any suitl able listening-key.

Her transmitter and the primary of her induction-cd1 are charged from any suitable current source. A ringing-generator 25 is adapted to be connected with the tip-conductor i2 ly means of springs 26, simultaneously depressed by means o1 any suitable ringing-key, while at the same time the sleeve-conductor is connected, through the fty-ohm coil 27, with the live pole of the battery B.` The operation of the provided with more than one station.

IOC

pairv of springs'28 serves to connectthe generator-with the sleeve side of the cord-circuit and t-he said resist ance with the tip side.

While the resistances employed for the various parts are not arbitrary, good results have been obtained with the cut-oft relays R2 of one hundred ohms resistance, the line-relays R of two hundred ohms, supervisory relays rando"l of two hundred ohms each, and V1o supervisory lamps of about ten or twelve volts. f

The operation of the invention will now be traced: Taking up the receiver at station A completes a path for current `from the bat.- ery B, over. conductor 9, through the line- 'relay R, over the sleeve-conductor 3, through `fthe -substation instruments, back to the cen- --tral oflice, over tip-conductor 2, and thence over branch 12 and spring 11 to ground. 2o This oper' tes the line-relay, which closes the local circuit o'f the lamp S, said local lcircuit being completed through the contacts of the V.relay R and the normal contacts of the cutoff relay R2. .ln response to this signal the operator inserts `the answering-plug P in the corresponding jack J, thereby completing a path `for current through the cut-off relay R2 from the live pole ot the battery B. This current-path may be traced as follows: 3o through-the supervisoryv lamp S2, the normal contacts of supervisory relay lr, branch 18, the tip-conductors oi the cord-circuit and to the acks, and thence through the winding of the rela;v to ground. `The cut-oil relay is 3 5 thus energizedA to open the circuit of the lamp S and to cut ofi the ground from the tip side of the line. Owing t-o the fact thatl the linecircuit is closed at the substation and the path to current through the cut-oli relay from 4o the tip side of the line is open, currentnow Hows in the same direction over the tipstrand 2, through the resistance 13, to the point 16, and thence through the winding ot vthe cut-o relay to (ground. A path for current is thus provide through the supervisory relay r, which is energized and opens the circuit of the supervisory lamp S2. The resistance 13 serves in the iirst instance to venable the cut-off relay R2 to operate, since with the 5cgrounded conductor 12 a short circuit oi said relay from the point 16 would otherwise resuit. Upon learning the order the operator tests the condition of the wanted line. Nor.- ymally it will be seen that the test-rings ot the jacks and the tip-conductors oi the calling ends of the cord-circuits are at the same potential, so that the testing of an idle line would not result in a iiow oi current and-no click would be received by the foperator.

During conversation, however, the said testrings are of substantially less potential, but the tip-conductor of the testing-cord is at the same pgtential, owing to the presence of the impedance-coils 2O and 21.

y seance current around through the grounded spring o'i the said relay.

insertion of the calling-plug closes a path for current through the lsupervisory lamp 'S3 and over the tip-strand vot the cord-circuit and through the cut-oli relay R2 -tov ground, the resistance 13 preventing the -shunting of said This prevents the operation yof the line-signal during the remainder of the connection.- The depi ession oi ringing-springs28 connects the calling-generator, with the vsleeve-conductor of the line, and thereby rings the bell at. station C. The tipspring 28 is connected through the low-resist ance path, including coil 27, thereby maintaining saiu relay operated during ringing. 8o

The depressioi'i oi springs 26 of the ringingkey connects generator 25 with the tip-conductor, which sends currentout over the line to operate the bell at station D, a low-resistance path being now completed over the 85 sleeve-strand through said coil 27.. The ringingcurrent it pulsating in character will maintain the vcut-ofi relay operated duringringing'; butI i1c it is alternating in character the said relay should be so, constructed as to respond thereto and remain actuated.v After ringing and before the subscribers response the supervisory signal S3 is lighted through the cut-off-relay path, and thus indicates the 'fact to the operator that the called subscriber 95 has not yet responded. Theresponse ot the subscriber closes a path tor current through the supervisory relay r2, thence over the sleeve side of the line, throu h the substation instruments, and back to idle central oilice, roo over the-tip-conductor, thence through the cut-oil relay to ground, thereby energizing said supervisory relay to open the circuit of the supervisory signal S3. During conversation the said resistances 13 are cut out o1e the circuit by the spring 17 ot the cut-oft` relay, it they be used. The path iorgtransinissioncurrent is irst over the sleeve-conductors ot the lines, and thence back -to 'the central oitice, over the tip-conductors. and through the cut-off relays to ground, and thence back to the other pole oi the battery. The impedance-coils 20 and 21 prevent short-circuiting the voice currents.

The transposition of the strands of the cord-circuit results in legging one cut-off relay from one side ot the through-circuit and the other cut-off relay from the other side of said circuit, by which arrangement a balanced line is secured. The several grounds vmentioned may beione and the'same or the common office return, Other changes may be. made inthe invention without departing from its scope or principle.

I claiin'-- f 1. In a telephone system, the combination with a telephone-line, of a cut-ofi relay legged to ground from one side of the line, a ground branch connected from the saine side of the A click is there- ,l line through the normal contacts of said re- 6 5 fore'redeived when a busy line is tested. The l lay, and-an artlficial reslstance between the connections of lsaid.; cut-H relay and` said branch with thelinewhereby when a' connecf `tien is established athena une, Seid relay is caused to operate;- substantially as de' scribed.

2. In a telephone system, the combination wlth'a telephone-Ime, of a-cut-of relay therefor, aresistance in the line to causecurrent 'to pass through the-cuto relay, and-means supervisory relay connected in parallel with y said linerelay when a connectlon is established, substantially as described.

l4. In a telephone system, the combination with a telephone-line having two limbs extending continuously through to the contacts of the spring-jacks upon the switchboard at vthe'central office, al line-signaling device and a source-of current connected with the l1ne at l the central office, a cut-off relay for the line Vpermanently connected therewith, a shunt of said cut-off relay for current in the line from said source when the subscriber is calling the central office, said shunt being controlled by the relay itself, and means for operatine' said relay by current over a portion of the talzking- "circuit when a connection is established means for including said source in the metallic line to furnish current tothe substation for talking when a connection is establlshed by said circuit with the line, said cut-off relay .being iny thepath of the latter current'a'nd adaptedl to be operated thereby during c onversation, whereby no current is wasted-'for the.. operation of said relay, substantially as descrrbed. Y l

6. In a telephone system, vthe combination' with -a telephone-line, ofzacentral sourcebf current, a Iline-relay adapted to be maintamed operated by current. in the line .whenever the circuit is closed at the substa# tion, a. cut-off relay for the'line havingits coil permanently connected between ,one limb of the lin'e and one pole of ,said source, a shunt for saidcut-oi relay maintained by its ownnormal contacts, whereby current in' the line, after the 'subscriber has removed his tion has been established with the line, will not pass through the coil of said 'cut-off relay,

6 5- telephone from the hookand before connecmeans to actuate said cut-off relay when a connection is established with the line and to maintain the actuation'by current in the line after the subscriber removes his tele'-4 phone fromt-he hook, substantially' as described.

7. In a telephone system, the combination with a tele hone-line, of a cut-ofi relay associated wit said line, a shunt of said cut-off relay maintained by its own normal con tacts, a central source of current one p'ole of which is ermanently connected with one limb of sald line throu h the coil of a line-relay, and the other po eof which is permanently connected tothe other limb of the line through -the coil of said normally shunted cut-eff relay, means for actuating said cutoff relay when a 'connectionis established v Y HARRY G. WEBSTER. Witnesses: v y

'ROBERT LEWIS. AMES, GAZELLA BEBER. 

